There are many ways to accomplish this while users are browsing your site. One way is to try to reduce the bounce rate (the visitors who have arrived at your site from a search engine and after just one page view, have then pressed the BACK button). But you already know that you can not have a rejection rate of 0%, right?

Wouldn’t be great to be able to monetize from users that quit from your site without clicking nor browsing in it? Definetely it is!